Ensure that the convection microwave is securely plugged into an electrical outlet. If the plug is not fully inserted in the outlet, unplug it and wait 10 seconds, then re-insert the plug into the outlet.
Plug another small appliance into the outlet and turn it on to ensure the outlet is working. Inspect the fuse or breaker box. Reset a tripped breaker or replace a blown fuse, if needed.
Ensure the convection microwave is programmed correctly. Check the control panel and set the timer. Test the oven to see if it is working properly.
Inspect the door, and fully engage the door safety lock. If the door is not fully closed, the oven will not function properly. If the oven still does not work correctly, have it inspected by a qualified service technician.